From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030243AbWGMQtB (ORCPT ); Thu, 13 Jul 2006 12:49:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030244AbWGMQtB (ORCPT ); Thu, 13 Jul 2006 12:49:01 -0400 Received: from rgminet01.oracle.com ([148.87.113.118]:47101 "EHLO rgminet01.oracle.com") by vger.kernel.org with ESMTP id S1030243AbWGMQtA (ORCPT ); Thu, 13 Jul 2006 12:49:00 -0400 Message-ID: <44B67961.4040600@oracle.com> Date: Thu, 13 Jul 2006 09:48:33 -0700 From: Zach Brown User-Agent: Thunderbird 1.5.0.4 (X11/20060614) MIME-Version: 1.0 To: "Raz Ben-Jehuda(caro)" CC: linux-aio@kvack.org, Xavier Roche , linux-kernel@vger.kernel.org Subject: Re: io_submit() taking a long time to return ? References: <44B5ED5F.1040606@exalead.com> <44B66A70.90502@oracle.com> <5d96567b0607130932g7ba6cf0jfebdb0af9c933000@mail.gmail.com> In-Reply-To: <5d96567b0607130932g7ba6cf0jfebdb0af9c933000@mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: AAAAAQAAAAI= X-Brightmail-Tracker: AAAAAQAAAAI= X-Whitelist: TRUE X-Whitelist: TRUE Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > what do u means by "sync block mapping " ? To find out what blocks to issue async IO against the submission path reads metadata from the file system that maps file regions to disk blocks. These metadata reads are synchronous and so can block the submitting task. The mappings tend to be cached, though, which is why this doesn't seem to be a problem in practice. - z